I'll give you a hint from talking to the interviewers
If it's on cars, football or computers...it has to be pretty special, they get 30-40 per week.
Pick something unusual or different, 6-8 slides and some dialogue about the pictures, not too deep but enough detail to keep them interested. On my day we had mixed martial arts, TVR, DJ-ing and alternative energy that were memorable, loads of footie that wasnt the least bit interesting to non "that club" people.